As soon as adjustment to the conditions of a given combination had been secured, it was a simple matter to anticipate, with a fair degree of accuracy, both a given letter and the recurrence of the sound. The attention could thus be pretty accurately divided between the two, and a very small time-displacement was the result. When I was acting as observer, a change of the auditory interval _upset_ the whole _plan_ of procedure for a short time. I had to accustom myself to the new rhythm. But as soon as this adjustment was made, it was just as easy to make the judgment at one rate as at another, barring variations which might be called fortuitous, since they were so small. This experience with the conditions here under consideration, as well as the introspections of the other observers, convinces me that the conception of an apperception-ripening time has been overworked. It is true that I find here, just as Pflaum[113] found, displacements in both directions with every observer. It seems very doubtful to me, however, whether these are in any sense due to what may be considered a fixed apperception-time for a given observer, under fixed objective conditions. The facility with which adaptation is made to the changed conditions of a new combination of intervals, so that just as small displacements are made under one as another, indicates to my mind that one can control the conditions so that the apperception shall ripen quickly or slowly, depending upon the warmth of the interest, and the concentration or division of the attention,--that there is a capacity in the ordinary individual so to adapt himself to the conditions as to do equally good work in coördinating two sense-impressions anywhere within a wide range of intervals. The influence of the length of the interval separating succeeding clicks, in determining displacements, has been considerably overestimated. I should state here that no one of the three observers had any specific training to reduce the displacement. The results were not discussed with them. They had no means of knowing what displacements they were making. This certainly adds strength to the inference, from these results, that there are adaptable apperceptive conditions for coördinating sense-impressions. THE INFLUENCE OF THE LENGTH OF THE SERIES OF VISUAL IMPRESSIONS